Ok this is what i d ( nothing wrong ith your phone)
All this is done using my Mobile..
I log onto my email and open the email from Realbotix
about half way down the page there is a link ( Realbotix Harmony 1.2.1 ) i click the link and start to download to my phone
My phone asks me if i want to download this app and if so i have to go to the "settings" on my phone and click the (allow download from unknown sourse) i click it and the app downloads to my phone.
once the app has finnished dowloading i click the icon and open the app, it asks me to log in i log in using my email address and password and it works fine.
It should work on your phone